This invention relates to a heat resistant thermoplastic resin compositions having good moldability. More particularly, it relates to resin compositions which comprise an aromatic polyether or a mixed resin of an aromatic polyether and a styrene resin (referred to as aromatic polyether resin hereinafter) and a fatty acid ester of polyhydric alcohols which has at least one --OH group.
Aromatic polyether resins have become noticeable as resins having wide uses because of their excellent mechanical properties, electrical characteristics and heat resistance with good dimensional stability. However, their serious defect is the low moldability.
U.S. Pat. No. 4,224,209, Japanese Patent Unexamined Publication (Kokai) No. 90559/77 and Japanese Patent Examined Publication (Kokoku) No. 5220/74 disclose the addition of plasticizers such as mineral oil, triphenyl phosphate, etc. to the aromatic polyether resins to solve said defect. However, when these plasticizers are added in an amount to give sufficient flowability for processing, heat resistance markedly decreases. Furthermore, Japanese Patent Unexamined Publications (Kokai) No. 79151/81 and No. 118956/80 disclose low molecular weight resinous materials such as low molecular weight polystyrene, coumarone-indene resin, polyterpene resin, modified rosin resin, etc. as additives which provide processing flowability without marked reduction of heat resistance. However, addition of these low molecular weight resinous materials to aromatic polyether resins results in much decrease of solvent cracking resistance (which means very easy cracking upon contact with chemicals). Besides, modified rosin resins are inferior in heat stability to cause discoloration.
The inventors have made intensive researches to improve processing flowability of aromatic polyether resins with no considerable decrease in their characteristics such as heat resistance, solvent cracking resistance, etc. As a result, it has been found that an especially preferred result is obtained with use of such compounds which are used as a lubricant or surfactant rather than as a plasticizer for aromatic polyether resins, namely, a fatty acid ester of polyhydric alcohols which has at least one --OH group.